You will still need ac power!

There is probably nothing wrong. Your un terminated cable is acting as an aerial and picking up mains hum. I assume that you will be connecting to a pre amp output rather than the speaker outlets from an amplifier!! The line sockets expect a 1volt p/p volume controlled input.

Actually, all you need is a line adapter, one for each speaker(B&O part). I dont remember the part number but it steps down and amplified signal to line level. One end of the cable is rca and the other is an old B&O speaker connector that you simply cut off. Once you have done that, you trim the cable and insert the bare wire into the receiver just like a regular speaker. Hope this helps.

Joe
 

Thanks for your reply.

The hum became muted when I connected it to the amp but did not disappear entirely. Moreover, this appears to be happening on only one speaker. The other speaker does not exhibit the same hum under similar conditions. This other speaker also has odd LED behavior - the green light appears even when there is no signal or even no connection. At times it also seems to display a sort of amber LED as if both the red and green LEDS were on. I tried cleaning the switches to no effect. This is very strange because the speakers were working fine until by B&O console died 2 weeks ago. Not sure what is going on but I cannot get sound out of them from the pre out on my NAD no matter what I do.

I also use Beolab 8000's with the pre-out of a NAD receiver. I also had only one speaker that buzzed as you describe. I took it to the service center and they 'cleaned the input board' or that's what it said on the work order. I've noticed that B&O don't use gold plated RCA connectors so they tend to oxidize like crazy - try powering off the speakers and getting a tight RCA connector, plug it in and rotate it around a lot. Or do something else to clean off the contacts of the connector. 

This one speaker would also power on randomly and start buzzing. It seems like the 'line in' feature of these beolabs is not very well thought out. If you get it working, you may also notice that when you power off the NAD, there's about 30 seconds of loud buzzing from both speakers before they power off - I choose to swich them off via a power conditioner rather than hear this.